Latch for contactors



Sept. 19, 1950 o. L. TAYLOR 2,523,163

LATCH FOR CONTACTORS Filed NOV. 28, 1947 Z2 21 F I 14 1 16 r 26 l I Z3 \I 1' g 31 I 24 I. I U i 4 s I 1 27 I g I l 13- 5 8 11 s 7 D g 10 WITNESSES: INVENTOR Owen LTny/ar W M6. W

ATTORNEY Patented Sept. 19, 1950 UNITED STATES PATENT omen:

LAT-CH FOR CONTACTORS Owen L. Taylor, Wilkin'sburg, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 28, 1947, Serial No. 788,377 7 6 Claims.

- This invention relates to a latching means for contactors and, more particularly, to latching mechanisms which are automatically operable to prevent failure of a contactor or switch under shock.

More specifically, this invention relates to an improvement on the type of latching mechanism shown in United States Patent No. 2,426,301, issued August 26, 1947, to Delbert Ellis and Owen L. Taylor. In Patent No. 2,426,301, there is shown latching mechanism for securing the armature of an electromagnetically-operated contactor against movement which is automatically operated in response to the application of shock to the support carrying the contactor. The latching operation is effected by the inertia of an oper ating member or mass which causes it to move relative to the contactor carrying support when such support is accelerated upon being subjected to shock. Actuation of the inertia responsive operating member is thus dependent upon the presence of an accelerating force and when such force decreases to a zero value or reverses in direction the operating member will return to a neutral position with the latching mechanism inoperative. The reversal of accelerating force will take place several times or continue until damped out when the support is subjected to shock. High speed pictures of shock responsive latching mechanism of a type shown in the above-mentioned patent have revealed that the latch follows the movement of the inertia responsive operating member and that the latch is actually withdra wn'from its latching position when the Operating member is returned to its neutral position. The apparatus is thus unlocked when the accelerating forces causing relative movement of the inertia responsive operating member decrease or pass through zero during reversal of their direction. This is entirely satisfactory for most shock conditions and does not result in failure or an uncontrolled movement of the apparatus being protected as the latch is immediately returned to latching position when the accelerating forces have reversed in direction and before such forces can build up to an extent sufficient to cause an uncontrolled movement of the apparatus being protected.

However, the camera studies do indicate that there exist very short periods in which the apparatus such as a contactor is unlatched and it is the principal object of this invention to provide an improved arrangement of mechanism for preventing the unlatching of the apparatus during such periods when the accelerating forces are decreasing or about to reverse in direction.

To this end, the inertia responsive operating mechanism of this invention is constructed of two parts connected together by a relatively stiff flat leaf spring. When the support carrying the inertia responsive operating mechanism is subjected to shock, the operating mechanism function in a normal manner to effect a latching operation as described in the above-mentioned patent. At the same time, energy is stored in the fiat leaf spring connecting the two parts which becomes effective when the accelerating force decreases to set up a very rapid movement which is effective to maintain the latch operated during those periods when the accelerating forces are decreasing or reversing in direction.

A more general object of this invention is to provide shock-responsive latching mechanism which is effective to maintain the latch in its operative latching position during the entire periodin which there are accelerating forces incident to shock.

A further object of this invention is to provide a shock-responsive latching device which is operated by inertia and is effective to maintain itself in a latching position during the entire time that the support carrying the mechanism latched thereby is subjected to forces incident to shock.

A further object of the invention is to provide latching mechanism having an operating member operable by inertia to effect a latching mechanism with resilient means for efiecting a latching operation of the operating member after the forces causing operation of the inertia member have decreased or at the time such forces reverse in direction.

Other objects and advantages of the invention will become apparent from the following description. 1

In the drawing there is shown a preferred enrbodiment of the invention. In this showing:

Figure 1 is a side elevational view of an electromagnetically-operated contactor, a part thereof being broken away and shown in section, having latching mechanism constructed in accordance with the principles of this invention, and

Fig. 2 i a broken'away side elevational view of the latching mechanism showing the relative position ofthe parts during acceleration thereby in response to the application of shock to the support carrying the contactor.

Referring to the drawing the numeral I designates a support having a contactor indicating as a whole by the numeral 2 mounted thereon. The

contactor 2 comprises electromagnetic oper ating mechanism 3, latching mechanism 4, and

a molded arcing chamber having an electrical contact structure mounted therein. The arcing chamber 5 is provided with a pair of stationary contacts 6 and l which are engageable, respectively, with movable contacts 8 and 9. The movable contacts 8 and 9 are positioned on the ends of an electrical conducting member In which is mounted in a saddle I, carried by a cross-bar |2 in accordance with conventional practice. The cross-bar I2 is mounted on an operating member l3 which is movable in a vertical direction from the position shown in Fig. l with the contacts disengaged to a contacts 3 and 9 with the stationary contacts 8 and The electromagnetic operating mechanism 3 is effective to move the contacts from their open position as shown in Fig. 1 to a closed position engaging the movable contacts 8 and 9 with the stationary contacts 6 and l. The electromagnetic operating mechanism 3 comprises a magnet frame l4 having an armature l5 mounted for vertical movement therein as viewed in Fig. 1 and to the lower end of which the operating member I3 is connected. The magnet frame is provided with a coil l5 which is effective upon energization thereof to move the armature l5 from the position shown in Fig. 1 to an upper position with the contacts in the arc box 5 engaged. The particular form of contact structure and operating mechanism therefore is a type well known in the art. This structure provides a gravity bias on the armature l5 which is effective to move the contactor to an open position upon deenergization of the coil IS.

A latch I! is mounted for sliding movement in guiding supports |8 connected to the frame I4 from an inoperative position as shown in Fig. 1, to a latching position engaged in notches I9 or 29, depending upon whether the contactor is open or closed. When the end of the latch H is engaged in the notches I9 or 20, the armature |5 will be latched against vertical movement. Sliding movement of the latch to and from its operating position is controlled by a lever 2| pivotally connected to the frame l4 by a pivot 22. The lever 2| is provided with a biasing spring, not shown, for moving it in a clockwise direction, disengaging the latch H from the armature [5. Upon movement of the lever 2| in a counterclockwise direction, the latch I! will be moved to the right as viewed in Fig. 1 into a latching position with its end engaged in one of the notches I9 or 20.

In order to impart counterclockwise movement to the lever 2| for moving the latch I! to its latching position an operating member 23 is provided. The operating member 23 is mounted for pivotal movement by a pivot 25 carried by lugs 24 connected to the frame [4 and extending through openings provided in the surface of the lever 2|. The operating member 23 is provided with camming surfaces 26 and 21 positioned on opposite sides of the pivot bar 25 which engage with the surface of the lever 2|. By this construction the lever 2| will be moved in a counterclockwise direction to effect the latching operation of the latch upon pivotal movement of the operating member 23 in either clockwise direction or counterclockwise direction.

A leaf spring 28 is provided for maintaining the operating member 23 in a normal position with both cam surfaces 26 and 21 engaged with the surface of the lever 2|. In order that the operating member 23 will be operative to effect position engaging the movable a latching operation when the support I is subjected to shock, a mass 29 is mounted on and connected to operating member 23 by a flat leaf spring 30. The mounting of the mass 29 is such that its center of gravity is displaced from the pivot 25 for a purpose to be described. The mass 29 is provided with a spring bumper 3| for a purpose to be described.

If the mass 29 and operating member 23 are considered as being one solid integral unit then the construction thus far described will be identical with that shown in Fig. 4 of Patent No. 2,426,301 to which reference is hereby made for a more complete description of its construction and operation. For the purposes of this invention, it will be sufiicient to point out that the inertia of the mass 29 due to its displaced center of gravity with respect to the pivot 25 is such that when the support is accelerated by the application of shock thereto, the mass 29 and operating member 23 will pivot about the pivot 25 relative to the support Assuming the initial movement to be in a downward direction, the camming surface 26 will operate to move the lever 2| in a counterclockwise direction to effect a latching operation. The latch I! will be maintained in a latching position as long as the downward force is continued. However, when such force decreases or approaches zero prior to reversal of the direction of motion, the spring 28 cooperating with the clockwise bias on lever 2| will function to return the operating member 23 to the position shown in Fig. 1. Upon reversal of the motion of the support the inertia of the mass 29 will be effective to pivot the operating member 23 in a counterclockwise direction with respect to the support I. This movement will cause the cam 21 to move the lever 2| in a counterclockwise direction to effect a latching operation as explained above. High speed camera studies of the apparatus have shown that the lever 2| follows the movement of the operating member 23, and intermediate reversals of motion, the latch IT is moved to an inoperative or unlatched position.

The novel structure of this invention involving the construction of the operating mechanism for the lever 2| in two parts comprising the operating member 23 and the mass 29 connected together by the fiat leaf spring 30 is effective to prevent the movement of the latch H to an unlatched position during those short intervals of time when the motion of the support incident to shock is reversed. The manner in which this is accomplished will be best understood by referring to Fig. 2 which shows the relative positions which the parts assume when the apparatus is initially accelerated in response to the application of shock to the support When shock is applied to the support in such a manner that its initial movement is in a downward direction, the combined inertia of the mass 29 and operating member 23 will effect a relative movement of the member 23 to cause the camming surface 25 to move the lever 2| in a counterclockwise direction to effect a latching operation as explained above. In addition to the latching operation, the inertia forces of the mass 29 will flex the leaf spring 3| by which it is connected to the operating member 23. If the accelerating force is sufficiently large, the spring bumper 3| will move into engagement with the operating member 23 to limit flexing of the springs 30 and at the same time store energy in this bumper spring 3|. When the accelerating force decreases sufficiently prior to its reversal in direction, the energy stored in the spring 30 and bumper spring 3| will become effective to move the mass 29 relative to'the operating member 23 and to flex the spring 30 in an opposite direction. This action causes the operating member 23 to move in a counterclockwise direction to move the camming surface 2! into engagement with the surface of the lever 2| to maintain the latch l I in its operative latching position. Due to the stiffness of the spring 30 and its high natural period of vibration compared to that of the mounting of the lever 2 i, the movement of the operating member 23 by the action of the spring 30 takes place at an extremely high rate which is much faster than can be followed by the lever 2|. Consequently, the latch I! is maintained in its operative latching position. If the support I stopped moving at this time, the member 23 would vibrate back and forth to maintain the latch operated until the vibratory movement of the mass 29 damped itself out. However, at the time the spring 30 becomes effective to move the camming member 2'! as just described, the direction of motion of the support I is reversing thereby introducing inertia forces effective to flex the spring 30 in an opposite direction from that shown in Fig. 2. These inertia forces will be effective to maintain the camming member 2! in engagement with the lever 2| as long as the reverse or upward movement of the sup-port l is continued. High speed camera studies have shown that the operating member in most cases performs only one oscillation at the time the direction of motion of the support I is reversed. However, such single oscillation is effective to prevent disengagement of the latch 17 at the time the direction of motion of its support is reversed. As a result, the latch I! is maintained in its operative latching position during the entire time the support I is mov ing back and forth incident to the application of a shock thereto.

It will thus be seen that at each reversal of the movement of the support I, the operating member 23 will move at an extremely rapid rate to prevent withdrawal of the latch. It will thus be seen that the improved structure of this invention is effective to maintain the latch in operative engagement during the entire time that the support is subjected to vibratory movement incident to the application of shock thereto.

Since numerous changes may be made in the above-described construction, and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A shock responsive latching device comprising a support, a structure movable relative to said support, a latch movable into an operative latching position for preventing movement of said structure, cam means pivotally mounted on said support for moving said latch to its operative latching position, and an inertia mass resiliently secured to said cam means radially of the pivot thereof.

2. A shock responsive latching device comprising a support, a structure movable relative to said support, a latch movable into an operative latching position for preventing movement of said structure, means for moving said latch to its operative latching position comprising an an operative position latching said part against movement, cam means for moving said latch to its latching position, an inertia mass, a spring mounting said inertia mass eccentrically on said cam means, the inertia of said mass being effective in response to movement of said device by the application thereto of a shock force to deflect said spring and move said cam means to operate said latch, the deflection force of said spring effecting an additional movement of said cam means for maintaining said latch in its operative latching position for a short period of time during which the movement of said device is stopping or reversing in direction.

5. A shock responsive latching device comprising, in combination, a support, a structure movable relative to said support, latch means movably mounted on said support for movement in a direction to engage and latch said structure, a cam, pivot means pivotally mounting said cam on said support in a position to engage said latch means in each of the two directions of rotation of said cam to bias said latch means to its position engaging and latching said structure, spring means biasing said cam to a neutral position in which said latch means is in its disengaged position, an inertia member, and a leaf spring securing said inertia member to said cam in a position radially disposed of the pivot means of said cam.

6. A shock responsive latching device comprising, in combination, a support, a structure movable relative to said support, a latch member slidably mounted on said support for movement in a direction to engage and latch said structure, a lever pivotally mounted on said frame and engaging said latch member to actuate said latch member to and from positions engaging said structure, a cam, pivot means pivotally mounting said cam on said support in a position to engage and move said lever in the same direction by rotation of said cam in each of its two directions of rotation to bias said latch member to its position engaging and latching said structure, spring means biasing said cam to a neutral position in which said latch is in its disengaged position, an inertia member, a leaf spring securing said inertia member to said cam in a position radially disposed of the pivot of said cam, and a resilient stop member engageable between said inertia member and said cam for limiting relative movement therebetween.

OWEN L. TAYLQR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 2,406,265 Syrovy Aug. 20, 1946 2,406,378 Immel Aug. 27, 1946 2,426,301 Ellis et a1 Aug. 26, 1947 

